Installing Ruby Gems with Native Extensions on Windows

If you’re stuck trying to run Ruby on Windows, one barrier you might have encountered is in trying to install a gem like ruby-debug or rdiscount. You’ll have seen an error like this:

%gem install ruby-debug
Building native extensions.  This could take a while...
ERROR:  Error installing ruby-debug:
        ERROR: Failed to build gem native extension.

C:/Ruby187/bin/ruby.exe extconf.rb
creating Makefile

'make' is not recognized as an internal or external command, operable program or batch file.

Gem files will remain installed in C:/Ruby187/lib/ruby/gems/1.8/gems/linecache-0.43 for inspection.
Results logged to C:/Ruby187/lib/ruby/gems/1.8/gems/linecache-0.43/ext/gem_make.out

That’s no fun.

The good news is, the lovely guys at Ruby Installer have put together a fix, called the DevKit. This installs the low-level bits and pieces needed to build those pesky native extensions on your Windows machine. There are a couple of manual steps which I didn’t find especially clear, so I’m documenting them here.

  • Download the DevKit self-extracting archive here
  • Run the archive, and when prompted, choose to extract it to C:\DevKit
  • When the archive has finished unpacking, open a command prompt in C:\DevKit and run
    ruby dk.rb init
    ruby dk.rb install
  • That’s it. You can test it using:
    gem install ruby-debug


Published by Matt

I write software, and love learning how to do it even better.

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  1. I’m afraid this did not help (Windows 7 Home Premium):-

    [C:\DevKit]ruby dk.rb init
    [INFO] found RubyInstaller v1.9.3 at C:/Ruby193

    Initialization complete! Please review and modify the auto-generated
    ‘config.yml’ file to ensure it contains the root directories to all
    of the installed Rubies you want enhanced by the DevKit.

    [C:\DevKit]b config.yml

    [C:\DevKit]ruby dk.rb install
    [INFO] RubyGems override already in place for C:/Ruby193, skipping.
    [INFO] Installing C:/Ruby193/lib/ruby/site_ruby/devkit.rb

    [C:\DevKit]cd –

    [C:\Indexing]gem install ruby-debug
    Fetching: rbx-require-relative-0.0.9.gem (100%)
    Fetching: linecache-0.46.gem (100%)
    ERROR: Error installing ruby-debug:
    The ‘linecache’ native gem requires installed build tools.

    Please update your PATH to include build tools or download the DevKit
    from ‘’ and follow the instructions
    at ‘’

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